The present invention provides compounds, pharmaceutical compositions containing one or more of those compounds or their pharmaceutically acceptable salts, which are effective in inhibiting the binding or function of various chemokines to chemokine receptors. As antagonists or modulators of chemokine receptors, the compounds and compositions have utility in treating various immune disorder conditions and diseases.
Chemokines, also known as chemotactic cytokines, are a group of small molecular-weight proteins that are released by a wide variety of cells and have a variety of biological activities. Chemokines attract various types of cells of the immune system, such as macrophages, T cells, eosinophils, basophils and neutrophils, and cause them to migrate from the blood to various lymphoid and none-lymphoid tissues. They mediate infiltration of inflammatory cells to sites of inflammation, and are responsible for the initiation and perpetuation of many inflammation diseases (reviewed in Schall, Cytokine, 3:165-183 (1991), Schall et al., Curr. Opin. Immunol., 6:865 873 (1994)).
In addition to stimulating chemotaxis, chemokines can induce other changes in responsive cells, including changes in cell shape, granule exocytosis, integrin up-regulation, formation of bioactive lipids (e.g., leukotrienes), respiratory burst associated with leukocyte activation, cell proliferation, resistance to induction of apoptosis and angiogenesis. Thus, chemokines are early triggers of the inflammatory response, causing inflammatory mediator release, chemotaxis and extravasation to sites of infection or inflammation. They are also stimulators of a multitude of cellular processes that bear important physiological functions as well as pathological consequences.
Chemokines exert their effects by activating chemokine receptors expressed by responsive cells. Chemokine receptors are a class of G-protein coupled receptors, also known as seven-transmembrane receptors, found on the surface of a wide variety of cell types such as leukocytes, endothelial cells, smooth muscle cells and tumor cells.
Chemokine receptor CCR2 is found on the surface of monocytes, macrophages, B cells, activated T cells, dendritic cells, endothelial cells and tumor cells. It is a receptor for a number of chemokine ligands, including MCP-1, MCP-2, MCP-3 and MCP-4. Among them, MCP-1 appears to interact only with CCR2, and not any other chemokine receptors identified so far.
CCR2 mediates migration of monocytes, antigen-presenting cells (also called dendritic cells) and lymphocytes to various tissues under inflammatory conditions. CCR2 has been implicated in the pathogenesis of a number of diseases, including atherosclerosis, restenosis, multiple sclerosis, pulmonary fibrosis, inflammatory bowel disease, rheumatoid arthritis, renal fibrosis, psoriasis, transplantation rejection, graft-versus-host disease, obesity, diabetes and cancer.
CCR2-mediated monocyte recruitment is one of the earliest steps that lead to the development of atherosclerosis. CCR2 is expressed by monocytes and is essential to migration of these cells to the artery well, where its ligand MCP-1 is highly expressed. In experimental models of atherosclerosis, arterial plague formation depends on the integrity of CCR2 and MCP-1, since deletion of either genes results in decreased atherosclerotic lesion formation in mice that otherwise develop severe disease (Gu et al., Mol. Cell. 2:275-81 (1998); Boring et al., Nature 394:894-7 (1998); Boring et al., J. Clin. Invest. 100:2552-61 (1997)).
In addition to many inflammation diseases, neuropathic pain is a condition in which CCR2 signaling may play a pathogenic role. It has been shown that the absence of CCR2 reduces inflammatory and neuropathic pain in mouse pain models, suggesting that recruitment and activation of macrophage and microglia to neural tissues play an important role in the pain states (Abbadie et al., Proc. Natl. Acad. Sci. USA. 100:13 (2003)). Small molecule antagonists of CCR2 described in this patent may useful in the treatment of chronic pain.
CCR2 has also been implicated in restenosis, the reclosure of the artery after balloon angioplasty. Studies in animal models have shown that restenosis is initiated, at least in part, by infiltration of monocytes to the site of artery injury. Deficiency of CCR2 or blockade of MCP-1 activity dramatically inhibits cell proliferation and expansion of the artery wall's inner lining (Furukawa et al., Circ. Res. 84:306-14 (1999); Egashira et al., Circ. Res. 90:1167-72 (2002); (Roque et al., Arterioscler. Thromb. Vasc. Biol. 22:554-9 (2002); Horvath et al., Circ. Res. 90:488-94 (2002); Egashira et al., FASEB J 14:1974-8 (2000)).
CCR2-mediated migration of monocytes is believed to be pathogenic in human multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS). CCR2 and MCP-1 expression is present in the cerebrospinal fluid (CSF) in MS patients. In a mouse model of human MS, namely the experimental autoimmune encephalomyelitis (EAE), deficiency in CCR2 or MCP-1 prevents the development of EAE (Izikson et al., Clin. Immunol. 103:125-31 (2002); Huang et al., J. Exp. Med. 193:713-26 (2001); Fife et al., J Exp Med 192:899-905 (2000); Karpus et al., J Leukoc. Biol. 62:681-7 (1997)).
CCR2 is required for infiltration of monocytes and macrophages to the lung. In the lung of chronic obstructive pulmonary disease (COPD) patients, an increased number of CD8+ lymphocytes, macrophages, eosinophils, granulocytes are present. Accumulation of inflammatory cells is associated with a remodeling response that leads to lung airway destruction. In a mouse model of pulmonary fibrosis, deficiency of CCR2 results in a marked reduction in inflammation and tissue fibrosis (Zhu et al., Immunol. 168:2953-62 (2002)).
CCR2 also appears to play a key role in idiopathic pulmonary fibrosis (IPF), another manifestation of severe lung inflammatory disorders. IPF is the scarring of the lung, characterized by the loss of lung elasticity and loss of alveolar surface area, leading to impairment of gas exchange and severe degradation in lung function. Inflammatory cell accumulation is one of the key features of IPF. In experimental models of IPF, CCR2 deficiency results in significant protection of lung fibrosis (Moore et al., J Immunol 167:4368-77 (2001); Gharaee-Kermani et al., Cytokine 24:266-76 (2003)).
CCR2 may be a mediator of idiopathic pneumonia syndrome (IPS) as well, a major complication after allogeneic bone marrow transplantation. Patients with IPS have elevated levels of MCP-1 in the bronchoalveolar lavage (BAL) fluid. In an experimental model of IPS, expression of MCP-1 and CCR2 mRNA increases significantly in the lung, and transplantation of CCR2-deficient donor cells results in a significant reduction in IPS severity compared with transplantation of wild-type cells. Moreover, neutralization of MCP-1 is efficacious in reducing lung injury (Hildebrandt, Duffner et al., Blood 103:2417-26 (2004)).
CCR2 appears to play a role in migration of T cells to the intestine, and may have a pathogenic role in Inflammatory bowel disease (IBD). Inflammatory bowel disease, consisting of ulcerative colitis and Crohn's disease, is associated with accumulation of inflammatory cells and destruction of the intestinal mucosal tissues. In the IL-10 knockout mice, which spontaneously develop ulcerative colitis, MCP-1 and CCR2 are among the chemokines and chemokine receptors to be significantly up-regulated as the disease progresses (Scheerens et al., Eur. J. Immunol. 31:1465-74 (2001)). In human IBD patients, the level of MCP-1 significantly increase in gut tissues (van Deventer, Aliment. Pharmacol. Ther. 11 Suppl 3:116-20; discussion 120-1 (1997); Mazzucchelli et al., J. Pathol. 178:201-6 (1996); Banks et al., J. Pathol. 199:28-35 (2003)).
Chemokines and chemokine receptors are expressed by intrinsic renal cells and infiltrating cells during renal inflammation (Segerer et al., J. Am. Soc. Nephrol. 11:152-76 (2000); Morii et al., J. Diabetes Complications 17:11-5 (2003); Lloyd et al. J. Exp. Med. 185:1371-80 (1997); Gonzalez-Cuadrado et al. Clin. Exp. Immunol. 106:518-22 (1996); Eddy & Giachelli, Kidney Int. 47:1546-57 (1995); Diamond et al., Am. J. Physiol. 266:F926-33 (1994)). In humans, CCR2 and ligand MCP-1 are among the proteins expressed in renal fibrosis, and are correlated with the extent of macrophage infiltration into the interstitium (Yang et al., Zhonghua Yi Xue Za Zhi 81:73-7 (2001); Stephan et al., J. Urol. 167:1497-502 (2002); Amann et al., Diabetes Care 26:2421-5. (2003); Dai et al., Chin. Med. J. (Engl) 114:864-8 (2001)). In animal models of renal fibrosis, blockade of CCR2 or MCP-1 leads to a marked reduction in severity of renal inflammation (Kitagawa et al., Am. J. Pathol. 165:237-46 (2004); Wada et al., Am. J. Pathol. 165:237-46 (2004); Shimizu et al., J. Am. Soc. Nephrol. 14:1496-505 (2003)).
Rheumatoid arthritis is a chronic disease of the joints characterized by synovial inflammation that leads to the destruction of cartilage and bone. Although the underlying causes of the disease are unknown, it is believed that macrophages and Th-1 type T cells play a key role in the initiation and perpetuation of the chronic inflammatory process (Vervoordeldonk et al., Curr. Rheumatol. Rep. 4:208-17 (2002)).
MCP-1 is among the several chemokines, including MIP-1α and IL-8, identified in rheumatoid synovium (Villiger et al., J. Immunol. 149:722-7 (1992); Scaife et al., Rheumatology (Oxford) 43:1346-52 (2004); Shadidi et al., Scand. J. Immunol. 57:192-8 (2003); Taylor et al., Arthritis Rheum. 43:38-47 (2000); Tucci et al., Biomed. Sci. Instrum. 34:169-74 (1997)). Chemokine receptors CCR1, CCR2, CCR3 and CCR5 are upregulated in the joints from arthritic mice (Plater-Zyberk et al., Immunol. Lett. 57:117-20 (1997). Blockade of MCP-1 activity using a CCR2 antagonist or an antibody against MCP-1 have been shown efficacious in reducing joint inflammation in experimental models of rheumatoid arthritis (Gong et al., J. Exp. Med. 186:131-7 (1997); Ogata et al., J Pathol. 182:106-14 (1997)).
CCR2-mediated infiltration of macrophages in the fat tissues may also contribute to the complications arising from obesity, a condition resulting from excessive storage of fat in the body. Obesity predisposes the affected individuals to many disorders, such as noninsulin-dependent diabetes, hypertension, stroke, and coronary artery disease. In obesity, adipose tissues have altered metabolic and endocrine functions that lead to an increased release of fatty acids, hormones, and proinflammatory molecules. Adipose tissue macrophages are believed to be a key source of proinflammatory cytokines including TNF-alpha, iNOS and IL-6 (Weisberg et al., J. Clin. Invest. 112:1796-808 (2003)). Recruitment of macrophages to the adipose tissue is likely mediated by MCP-1 produced by adipocytes (Christiansen et al., Int. J. Obes. Relat. Metab. Disord. (2004); Sartipy et al., Proc. Natl. Acad. Sci. U.S.A. 100:7265-70 (2003)).
Elevated MCP-1 may induce adipocyte differentiation and insulin resistance, and contribute to pathologies associated with hyperinsulinemia and obesity. MCP-1 is overexpressed in plasma in obese mice compared to lean controls and white adipose is a major source. MCP-1 has also been shown to accelerate wound healing, and has a direct angiogenic effect on epithelial cells, and may play a direct role in the remodeling of adipose tissue in obesity. (PNAS, 2003, 100, 7265).
MCP-1 plasma levels are substantially increased in Diet Induce Obesity (DIO) mice, and a strong correlation between plasma MCP-1 levels and body weight has been identified. Furthermore, elevation of MCP-1 induced by high fat diet causes changes in the CD11b positive monocyte population in DIO mice. (J Biol Chem, 2003, 46654).
Furthermore, chronic inflammation in fat is thought to play a crucial role in the development of obesity-related insulin resistance (J Clin Invest., 2003, 1821). It has been proposed that obesity related insulin resistance is, at least in part, a chronic inflammatory disease initiated in adipose tissue. Many inflammation and macrophage specific genes are dramatically upregulated in white adipose tissue in mouse models of genetic and high fat diet-induced obesity (DIO), and this upregulation precedes a dramatic increase in circulating insulin.
Increased expression levels of monocyte CCR2 and monocyte chemoattractant protein-1 in patients with diabetes mellitus (Biochemical and Biophysical Research Communications 2006, 344(3), 780-5) were found in a study involving diabetic patients. Serum MCP-1 concentrations and surface expression of CCR2 on monocytes in diabetic patients were significantly higher than in non-diabetics, and the serum MCP-1 levels correlated with HbA1c, triglycerides, BMI, hs-CRP. Surface expression levels of CD36 and CD68 on monocytes were significantly increased in diabetic patients and more unregulated by MCP-1 in diabetics, augmenting uptake of ox-LDL, and hence potentially foam cell transformation. Elevated serum MCP-1 and increased monocyte CCR2, CD36, CD68 expression correlated with poor blood glucose control and potentially correlate with increased vessel wall monocyte recruitment.
MCP-1 is a potential player in negative cross talk between adipose tissue and skeletal muscle (Endocrinology 2006, 2458). MCP-1 can significantly reduce insulin-stimulated glucose uptake, and is a prominent inducer of insulin resistance in human skeletal muscle cell. Adipose tissue is a major secretory and endocrine active organ producing bioactive proteins regulating energy metabolism and insulin sensitivity.
CCR2 modulates inflammatory and metabolic effects of high-fat feeding (J Clin Invest., 2006, 115). Genetic deficiency in CCR2 reduced food intake and attenuated the development of obesity in mice fed a high fat diet. In obese mice matched for adiposity, CCR2 deficiency reduced macrophage content and inflammatory profile of adipose tissue, increased adiponectin expression, and improved glucose homeostatis and insulin sensitivity. In lean animals, no effect of CCR2 genotype on metabolic trait was found. In high-fat diet mice, CCR2 genotype modulated feeding, the development of obesity and adipose tissue inflammation. Once established, short term antagonism was shown to attenuate macrophage accumulation in adipose tissue and insulin resistance.
Chemokine and chemokine receptors are the key regulators of immune cell trafficking. MCP-1 is a potent chemoattractant of monocytes and T cells; its expression is induced under inflammatory conditions including proinflammatory cytokine stimulations and hypoxia. The interaction between MCP-1 and CCR2 mediates migration of monocytes, macrophage as well as activated T cells and play a key role in the pathogenesis of many inflammatory diseases. Inhibition of CCR2 functions using small molecule antagonists described in this invention represents a new approach for the treatments of inflammatory disorders.
Psoriasis is a chronic inflammatory disease characterized by hyperproliferation of keratinocytes and pronounced leukocyte infiltration. It is known that keratinocytes from psoriasis lesion express abundant CCR2 ligand MCP-1, particularly when stimulated by proinflammatory cytokines such as TNF-α (Vestergaard et al., Acta. Derm. Venereol. 84(5):353-8 (2004); Gillitzer et al., J. Invest. Dermatol. 101 (2): 127-31 (1993); Deleuran et al., J. Dermatol. Sci. 13(3):228-36 (1996)). Since MCP-1 can attract migration of both macrophages and dendritic cells expressing CCR2 to the skin, this receptor and ligand pair is believed to be important in regulating the interaction between proliferating keratinocytes and dermal macrophage during the development of psoriasis. A small molecule antagonist may thus be useful in the treatment of psoriasis.
In addition to inflammatory diseases, CCR2 has also been implicated in cancers (Broek et al., Br J Cancer. 88(6):855-62 (2003)). Tumor cells stimulate the formation of stroma that secretes various mediators pivotal for tumor growth, including growth factors, cytokines, and proteases. It is known that the level of MCP-1 is associated significantly with tumor-associated macrophage accumulation, and prognostic analysis reveals that high expression of MCP-1 is a significant indicator of early relapse in breast cancer (Ueno et al., Clin. Cancer Res. 6(8):3282-9 (2001)). A small molecule antagonist of CCR2 may thus be able to reduce the release of growth-stimulating cytokines by blocking accumulation of macrophages at sites of tumor formation.
T lymphocyte (T cell) infiltration into the small intestine and colon has been linked to the pathogenesis of Coeliac diseases, food allergies, rheumatoid arthritis, human inflammatory bowel diseases (IBD) which include Crohn's disease and ulcerative colitis. Blocking trafficking of relevant T cell populations to the intestine can lead to an effective approach to treat human IBD. More recently, chemokine receptor 9 (CCR9) has been noted to be expressed on gut-homing T cells in peripheral blood, elevated in patients with small bowel inflammation such as Crohn's disease and celiac disease. The only CCR9 ligand identified to date, TECK (thymus-expressed chemokine) is expressed in the small intestine and the ligand receptor pair is now thought to play a pivotal role in the development of IBD. In particular, this pair mediates the migration of disease causing T cells to the intestine. See for example, Zaballos, et al., J. Immunol., 162(10):5671 5675 (1999); Kunkel, et al., J. Exp. Med. 192(5):761-768 (2000); Papadakis, et al., J. Immunol., 165(9):5069 5076 (2000); Papadakis, et al., Gastroenterology, 121(2):246 254 (2001); Campbell, et al., J. Exp. Med., 195(1):135 141 (2002); Wurbel, et al., Blood, 98(9):2626-2632 (2001); and Uehara, et al., J. Immunol, 168(6):2811-2819 (2002).